It has been known that many types of products are packaged in containers obtained from cardboard blanks supplied in a flat folded tubular shape, in the specific technical field also known as pre-stuck blanks not in volume. The flat folded blanks must be collected singularly and successively opened out and erected in the tubular shape to enable the insertion of the articles to be packaged.
In the packaging field, various typologies of apparatuses have been known which allow to pick up flat folded tubular blanks from a store, erect such blanks in a tubular shape and feed them to a transport line of the packaging machine, actuated stepwise to bring the opened blanks at the operating station where insertion of the articles to be packaged is carried out. Such apparatuses generally comprise gripping means suitable to grip single tubular blanks and to extract them singularly from a store, where the blanks are prearranged in a flat folded shape, and folder means suitable to open out the blanks in a tubular shape.
Patent application EP 2 108 505 illustrates a device for erecting flat folded tubular blanks comprising a collecting group provided with first gripping means which are mobile between a pick up station of single tubular blanks from a store and an opening station of single tubular blanks. In the opening station is arranged an opening group which is provided with second gripping means for gripping the single flat folded tubular blanks at a second face, opposite to the first face engaged by the first gripping means. The second gripping means are mobile between a gripping position of the single tubular blanks and an opening position, spaced from the gripping position. A folder member is used to progressively engage a free side of the single tubular blanks during the opening course, to complete the erecting of the tubular blanks.
Patent EP 1 419 969 illustrates a device for gripping and erecting cardboard blanks comprising an arm swinging between a first position, wherein it picks up a blank from a feeding station, and a second position, wherein it releases the same blank after having erected it. The swing arm carries first and second suction means which engage the blank on opposite surfaces. The first suction means are integral to the swing arm, while the second suction means are carried by a crown wheel sector which is meshed with a toothed wheel rotating on the swing arm. The toothed wheel is handled by a crank mechanism controlled by a four-bar linkage, suitably driven with a reciprocating drive motion.
The known solutions do not fully satisfy the current exigencies of the users. In fact, known apparatuses are in general complex from a point of view both constructional and functional. In particular, it is complained that such apparatuses require a plurality of members to operate in sequence in different operating stations to carry out the cited phases of picking up single blanks from the store where they are arranged flat folded, of opening and erecting the blanks and of feeding the opened blanks to the transport line of the packaging machine where is performed the insertion of the articles to be packaged. This obviously implies high costs, greater risks of failure and proportionally reduced speeds which limit the productivity of the packaging machines, further that difficulties in the use for the users.